Piscivore diet response to a collapse in pelagic prey populations

Zeug, Steven C.; Feyrer, Frederick; Brodsky, Annie; Melgo, Jenny

doi:10.1007/s10641-017-0618-x

Cited by 10 publications

(11 citation statements)

References 34 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Mysid shrimp were included in the second objective because they were once predominant prey for many juvenile fish species in the upper estuary. They are now relatively rare in the diets of these same fishes (Feyrer et al 2003;Zeug et al 2017), but little is known about their distribution between shallow and deep waters. Mysid shrimp abundance declined in the upper estuary after the introduction of the Overbite clam Potamocorbula amurensis, which caused a dramatic reduction in primary producer biomass, which is a major food source of mysid shrimp (Orsi and Mecum 1996).…”

Section: Forage Fish Larvae Distribution and Habitat Use During Contrmentioning

confidence: 99%

Forage Fish Larvae Distribution and Habitat Use During Contrasting Years of Low and High Freshwater Flow in the San Francisco Estuary

Grimaldo¹,

Burns

Miller³

et al. 2020

SFEWS

View full text Add to dashboard Cite

Recruitment of estuarine organisms can vary dramatically from year to year with abiotic and biotic conditions. The San Francisco Estuary (California, USA) supports a dynamic ecosystem that receives freshwater flow from numerous tributaries that drain one of the largest watersheds in western North America. In this study, we examined distribution and habitat use of two forage fish larvae of management interest, Longfin Smelt Spirinchus thaleichthys and Pacific Herring Clupea pallasii, during a low-flow and a high-flow year to better understand how their rearing locations (region and habitat) may affect their annual recruitment variability. During the low-flow year, larval and post-larval Longfin Smelt were distributed landward, where suitable salinity overlapped with spawning habitats. During the high-flow year, larval Longfin Smelt were distributed seaward, with many collected in smaller tributaries and shallow habitats of San Francisco Bay. Local spawning and advection from seaward habitats were speculated to be the primary mechanisms that underlie larval Longfin Smelt distribution during the high-flow year. Larval Pacific Herring were more abundant seaward in both years, but a modest number of larvae were also found landward during the low-flow year. Larval Pacific Herring abundance was lower overall in the high-flow year, suggesting advection out of the area or poor recruitment. Future monitoring and conservation efforts for Longfin Smelt and Pacific Herring should recognize that potential mechanisms underlying their recruitment can vary broadly across the San Francisco Estuary in any given year, which suggests that monitoring and research of these two species expand accordingly with hydrologic conditions that are likely to affect their spawning and larval rearing distributions.

show abstract

Section: Forage Fish Larvae Distribution and Habitat Use During Contrmentioning

confidence: 99%

Forage Fish Larvae Distribution and Habitat Use During Contrasting Years of Low and High Freshwater Flow in the San Francisco Estuary

Grimaldo¹,

Burns

Miller³

et al. 2020

SFEWS

View full text Add to dashboard Cite

show abstract

“…During most of the overbite clam era, Striped Bass research and diet studies have been a lower priority than endangered species research. Visual searches of Striped Bass stomach contents did not reveal evidence of predation on Delta Smelt (Nobriga and Feyrer 2007;Zeug et al 2017), though DNA-based methods were able to do so (Schreier et al 2016;Michel et al 2018).…”

Section: The Overbite Clam and Ecological Regime Shift (1987−present)mentioning

confidence: 89%

“…A similar dynamic might involve Striped Bass. The high mobility (Scofield and Bryant 1926;Sabal et al 2019) and diverse diet compositions (Nobriga and Feyrer 2008;Zeug et al 2017) of Striped Bass suggest they have limited reliance on individual prey taxa once they survive their first few months of life. Striped Bass can opportunistically switch prey based on the composition of the available prey field; thus, Striped Bass can be a source of minor per capita changes in predation rates on multiple prey populations that might result in substantial changes in juvenile survival rates, and unanticipated population consequences for prey populations.…”

Section: Did a Shifting Ecological Baseline Mask The Predatory Effectmentioning

confidence: 99%

“…Thus, density-dependent predation is analogous to a Type-III functional response (Nobriga et al 2013). Prey choices by Striped Bass in the San Francisco Estuary have previously been shown to be [prey] density-dependent (Nobriga and Feyrer 2008;Zeug et al 2017).…”

Section: Density-dependent Prey Consumptionmentioning

confidence: 99%

“…The quantitative dynamics of predator−prey interactions are governed by a functional response, which affects how prey are chosen, and an aggregative response, which affects how many predators get involved (Essington and Hansson 2004). The use of individual prey species by Striped Bass reflects changes in prey abundance across multiple spatio-temporal scales (Nobriga and Feyrer 2008;Nobriga et al 2013;Zeug et al 2017). It is important to view historical observations of Delta Smelt as prey in the light of this density-dependent prey consumption because it indicates that Striped Bass use of Delta Smelt as prey is related to the density of Delta Smelt and Delta Smelt's density relative to other potential prey species.…”

Section: March 2020mentioning

confidence: 99%

See 2 more Smart Citations

Did a Shifting Ecological Baseline Mask the Predatory Effect of Striped Bass on Delta Smelt?

Nobriga¹,

Smith²

2020

SFEWS

View full text Add to dashboard Cite

Striped Bass, Morone saxatilis, has been an established member of the San Francisco Estuary's (estuary's) aquatic community for nearly a century and a half. As a predator, it has the potential to shape community composition through top-down control of lower trophic species, including the endangered Delta Smelt, Hypomesus transpacificus. Invasive predators can be particularly disruptive to native communities because they present novel dangers to naïve populations, but, as a long-established member of the aquatic community, Striped Bass has not previously been considered to limit the Delta Smelt population. Here, we develop an argument that Striped Bass are important to controlling Delta Smelt. We support this argument by reviewing historical data which suggests that declines in Delta Smelt before the current-day monitoring program were driven by the invasion of Striped Bass into the estuary. We describe this phenomenon as the 'phantom predator' hypothesis in the context of an analog to the shifting baseline syndrome previously described for marine fisheries. A deeper understanding of how well studied (and rapidly changing) bottomup drivers of the estuary food web interact with poorly understood (but also rapidly changing) controls at the top of the food web could prove very important to the conservation of other declining native fishes and possible future attempts to reintroduce captive-reared Delta Smelt to the estuary.

show abstract

Enumerating Predation on Chinook Salmon, Delta Smelt, and Other San Francisco Estuary Fishes Using Genetics

Brandl

Schreier²,

Conrad³

et al. 2021

N American J Fish Manag

View full text Add to dashboard Cite

The establishment of non-native predator fish is a worldwide phenomenon often having adverse effects on native species. Trophic interactions are complex, and uncertainty is a common theme in discussions of non-native predator management. Several fishes of the San Francisco Estuary have experienced significant declines in recent decades due to multiple factors, including habitat alteration and predation. The role of predation as a direct cause of mortality remains an open question, as does whether habitat conditions play a role in promoting predation on species of concern. Recent studies using visual identification of prey have found little to no evidence of predation on ESA-listed species such as Delta Smelt Hypomesus transpacificus and juvenile Chinook Salmon Oncorhynchus tshawytscha. To increase the likelihood of detecting predation, this study employed a genetic approach. We combined this technique with habitat and water quality data to investigate the role habitat may be playing on incidence of predation. This study focused on detection of predation on Chinook Salmon and Delta Smelt, as well as 6 other native fishes, and 6 non-native fishes by Striped Bass Morone saxatilis, and other piscivores. Unlike previous studies in the region, the proportion of predators with no prey detected in their gut contents was high (47-81%). The study detected Delta Smelt in 1.3% of Striped Bassconsiderably higher than other contemporary predation studies in the Delta. In the month of April 2014, 6.6% of Striped Bass were positive for Chinook Salmon-substantially higher than recent visual diet studies in the Delta. Interestingly, native species comprised a relatively high proportion of Striped Bass prey (60%). Water temperature and conductivity were identified as significant predictors of Chinook Salmon presence in Striped Bass gut contents. This research

show abstract

Piscivore diet response to a collapse in pelagic prey populations

Cited by 10 publications

References 34 publications

Forage Fish Larvae Distribution and Habitat Use During Contrasting Years of Low and High Freshwater Flow in the San Francisco Estuary

Forage Fish Larvae Distribution and Habitat Use During Contrasting Years of Low and High Freshwater Flow in the San Francisco Estuary

Did a Shifting Ecological Baseline Mask the Predatory Effect of Striped Bass on Delta Smelt?

Enumerating Predation on Chinook Salmon, Delta Smelt, and Other San Francisco Estuary Fishes Using Genetics

Contact Info

Product

Resources

About